I never write comments on KZitem, but I just cannot not do it here. I am already in Masters studying Materials Science and never have I ever experienced such a fascination with that subject as during your lectures. None of my Professors ever managed to explain everything in such detail and also so simple. It is true what they say: "Only the one who can explain the most difficult things in a simple, understandable way has achieved the true Mastery". Thank you soooo much, Sir. I am a student from Russia now studying in Germany and I am a big fan. Thank you for your work it trully is lifechanging!
@rizazo1212
3 жыл бұрын
Ikr! This is poetry!
@vivekkumarnayak2819
5 жыл бұрын
Helpful video and great thank u...sir concept clear ho gya sir
@tumiltyniall8785
3 жыл бұрын
These are excellent lectures, your students are very lucky to have you as is IIT.
@annalisagenovesi2275
6 жыл бұрын
Thanks for publishing these videos, they are very interesting and stimulating. (I'm watching from Italy)
@introductiontomaterialsscience
5 жыл бұрын
Thanks for your comment. I have pleasant memories of my one month stay at Trento in 2014. Rajesh Prasad
@dhruvpendharkar488
3 жыл бұрын
Sir, in a book that I am referring(physical metallurgy principles and practices by V. Raghavan, page 15), delta Hf is defined as reversible work done at constant pressure in bringing an atom from inside the crystal to the surface. But, I did not understand what pressure means for solids and even if we define it for solids , why does it remain constant in the process of removal of vacncy . I would also like to add that I am finding these videos very informative and enjoyable an am extremely thankful for the oppurtunity to watch these videos.
@introductiontomaterialsscience
3 жыл бұрын
You don't have to think in terms of pressure. Work can be done on atom simply in terms of Forcexdisplacement. But I do not know how to do this for this situation. Thus bond breaking approach appareas more convenient to me. If you can share the book I can have a look.
@dhruvpendharkar488
3 жыл бұрын
Thank You for your time sir. Yes, I can share the book pdf. May I please know how I can reach you ? Also Sir , in the experimental method for finding fraction of vacancies , I did not understand how it gives us total vacancy fraction after thermal expansion as we actually compute (delta N)/N . How do we account for previous vacancies that contribute to the vacancy fraction in addition to new ones ? Or do we assume there were no vacancies prior to expansion ?
@introductiontomaterialsscience
3 жыл бұрын
@@dhruvpendharkar488 I did not mean that you share the pdf. You can just share the name of the author and book and the page number.
@dhruvpendharkar488
3 жыл бұрын
@@introductiontomaterialsscience Physical metallurgy principles and practices by V. Raghavan, page 15
@ibrahemnaser3832
4 жыл бұрын
Great video as usual, thank you. Greetings from Egypt.
@gomaa2020
4 жыл бұрын
hello, Egypt :)
@anmolrattan1828
4 жыл бұрын
Thank you , sir Even my college teachers are not able teach this concept.
@beckwalter8047
4 жыл бұрын
Me too
@commonindianbirds223
2 жыл бұрын
Sir, how does enthalpy increase when the bond is broken. Enthalpy is the sum of internal energy+ product of pressure and volume. So when the bond is broken, energy stored in the form of bonds is lost and thus the internal energy decreases. But you say that enthalpy increases. Can you please clear my doubt Sir?
@ankitk49
4 жыл бұрын
Sir if solid solutions are filled with point defects, can we calculate their solubility limit by the same idea as we used for equilibrium concentration of vacancies? (just a thought)
@rajeshprasadlectures
4 жыл бұрын
I think it should be possible and we should be able to get the equation of the solvus line in the phase diagram. Haven't tried it myself. But seems like an interesting idea.
@ankitk49
4 жыл бұрын
@@rajeshprasadlectures thank you sir for replying to my query. I want to try it after completing the phase diagram lectures. Could you tell me how else can I reach you?
@suwarnaca9595
5 жыл бұрын
y did we take V instead of v in the diff for delta V?
@shivampratap8863
3 жыл бұрын
I think its a typo error, I m not sure
@Pro-dq9ey
4 жыл бұрын
22:48 Sir started drinking water? 😂
@siddharthjena2189
2 жыл бұрын
Sir why are vacancies called as thermodynamically stable defects? Only because of they are stable at higher temperatures?? Are line defects also thermodynamically stable?? If not then why?? Thank you
@bestcakesdesign
3 жыл бұрын
I think it will not come in competition exam but i watch because i like the great concepts..
@ceeejaey
4 жыл бұрын
Loved how you squeezed in a life lesson along with material science at 0:26
@rajeshprasad101
4 жыл бұрын
🙂
@HarshRajAlwaysfree
3 жыл бұрын
It was a really good video
@pankajojha5075
4 жыл бұрын
Sir can we consider point defect as a defect which is in thermodynamic equilibrium?
@introductiontomaterialsscience
4 жыл бұрын
Yes, that is the basis for the calculation of the equilibrium concentration of vacancies.
@amitpradhan7016
3 жыл бұрын
How the 4 microstates corresponds to 1 macrostates
@bestcakesdesign
3 жыл бұрын
It means in defect no atom loses it unit cell?
@yannickkamta2719
4 жыл бұрын
Good morning sir! and thank you for your great lessons. About the effect of temperature on the vacancy creation. In case of Zinc oxide nanoparticles, it is known that annealing the ZnO in H2 or N2 at higher temperatures (200-300 degree Celcuis) increases the number of oxygen vacancies, now my question is that: if after annealing I use my sample at room temperature, the vacancies created will be still here ? please help me to understand it!
@rajeshprasad101
4 жыл бұрын
No, on slow cooling vacancy concentration will come back to its equilibrium value at room temperature.
@MrMarlaaditya
4 жыл бұрын
Thank you sir. If an external "ion" occupies an interstitial site in crystal, can that cause lattice contraction in the crystal?
@introductiontomaterialsscience
4 жыл бұрын
I think it is possible.
@MrMarlaaditya
4 жыл бұрын
@@introductiontomaterialsscience thank you sir.
@Riya_njoying
3 жыл бұрын
Is Law of Mass conservation applicable for vacancy ?
@introductiontomaterialsscience
3 жыл бұрын
It is applicable to the following process: Crystal with less number of vacancy --> Crystal with higher number of vacancies. The mass is the same before and after the creation additional vacancies as the total number of atoms do not change. The vacancies are not created by the destruction of atoms but only their displacement from a regular site to some other site like free surfaces, grain boundaries, dislocations etc.
@Riya_njoying
3 жыл бұрын
@@introductiontomaterialsscience Thank you for the answer. Will it be applicable for interstitial diffusion ?
@introductiontomaterialsscience
3 жыл бұрын
@@Riya_njoying Yes mass conservation is again applicable in the sense that total (mass of solvent atoms + total mass interstitial solute atoms) remains the same before and after the diffusion.
@Dileepkumar-pd6ce
6 жыл бұрын
If crystal with vacancies have lower free energy than pure crystal, then why in the graph the free energy increased with increase in no.of vacancies?
@ashishgarg929
6 жыл бұрын
It is because of enthalpy, you have to provide extra energy to break the bond and create vacancy
@introductiontomaterialsscience
5 жыл бұрын
Free energy initially decreases with addition of vacancies. But then it reaches a minimum value and subsequently starts to increase. The minimum correspond to the equilibrium number of vacancies.
@ibrahimnazemqader9153
6 жыл бұрын
thanks a lot
@aswathikoorikkat6361
4 жыл бұрын
what happens once you pass the 'neq' value?
@introductiontomaterialsscience
4 жыл бұрын
neq is the equilibrium value, i.e., G is minimum at this point. Thus either for n>neq or n
@venkateshnarayan
3 ай бұрын
@@introductiontomaterialsscience Sir it means the Gibbs free energy for any crystal can't be more than zero.
@NeetipudiSubash
6 жыл бұрын
Thank you sir
@kanakarajulinga9596
3 жыл бұрын
Sir , here what is mean by free energy??
@introductiontomaterialsscience
3 жыл бұрын
It is the Gibbs free energy G as defined in classical thermodynamics by G=H-TS where H is the enthalpy and S is the entropy and T is the absolute temperature. At constant tempearture and pressure a system attains equilibrium by minimizing its Gibbs free energy.
@ibrahimnazemqader9153
6 жыл бұрын
I am wonder how (ln N!=0) ?!!!!!!!!!!! I get different result from my calculator!
@manasmahata271
5 жыл бұрын
lnN!=0 when N=1.....ln1!=ln1=0
@abhirupchakraborty9027
4 жыл бұрын
If the enthalpy of motion of a vacancy is 100 kJ mol-1 , the time that a vacancy takes to jump to an adjacent site at 25° C is about a) 3×10^17 s b) 10^13 s c) 2×10^26 s d) 3×10^4 s Pls solve
@monishreddy1797
4 жыл бұрын
you got the answer?
@abhirupchakraborty9027
4 жыл бұрын
@@monishreddy1797 No.. thats why I asked the question
@k_j4845
4 жыл бұрын
Thank you sir!
@arneetkaur1001
4 жыл бұрын
Thank you Sir.
@prakhartiwari6433
4 жыл бұрын
What point defects are possible for Al2O3 as an impurity in MgO? How many Al3+ ions must be added to form each of these defects? Sir please help me
@introductiontomaterialsscience
4 жыл бұрын
MgO is NaCl structure with Cl at FCC locations and O in OH voids. There is one cation Mg for every anion O. If you add Al2O3 then you are supplying only two cations (Al) but three anions (O). Thus one cation vacancy will be created for every Al2O3 molecule added.
@prakhartiwari6433
4 жыл бұрын
@@introductiontomaterialsscience thank you sir... 😊
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